The present invention relates to a method of extracting a compound from vegetable material, wherein the vegetable material is reduced in size, subjected to an extraction treatment using a solvent, after which the undissolved parts are separated from the solvent comprising the compound.
This type of method is quite old. Examples are the infusion of tea and the preparation of tinctures. In both cases the undissolved parts are usually separated from the solvent comprising the compound. This may be accomplished by, for example, filtering or centrifugation.
The disadvantage with the known methods is that to a lesser or greater degree the active compound(s) stay behind in the separated insoluble parts.
The object of the present invention is to provide a method as described in the preamble, by which the yield of active compound can be increased.
To this end the method is characterized in that the vegetable material is frozen using a liquified gas and in frozen condition reduced in size prior to being extracted with the solvent.
In this invention the vegetable material is effectively opened up and a higher percentage of yield is assured. Liquid nitrogen is very suitable for this purpose because of its inert (non-oxidative) nature and low price.
European patent 0 477 968 describes a method of preparing an extract of Ginkgo biloba by treating the leaves with aqueous acetone, an aqueous alkanol with 1 to 3 C atoms, or anhydrous methanol at a temperature of 40-100xc2x0 C. After the removal of solid parts, this solution is treated with ammonium sulphate, methyl ethyl ketone, and the resulting extract is extracted with a higher alkanol. After several additional steps an extract is obtained comprising 20 to % by weight of flavoglycosides, 2.5 to 4.4% by weight of ginkgolides A, B, C and J, and 2.0 to 4.0% by weight of bilobalide. The described method of extraction is very laborious.
European patent 0 431 535 describes a method of preparing an extract from Ginkgo biloba leaves that essentially corresponds with the method described above. In addition, lead salt is used for further purification. For this reason this extraction method is also very laborious while moreover using a lead compound that is bad for both the environment and human health.